In past, there has been commercially available a battery device equipped with; a case formed in a rectangular shape having a width in a left-to-right direction, a thickness in an up-and-down direction, and a length in a front to rear direction, with an upper surface anal a lower surface opposite thereto in the up-and-down direction, and a front surface and a rear surface opposite thereto in the length direction; a charging unit disposed inside the case; and a battery side terminal connected to the charging unit and disposed on the front surface of the case (for example, see Japanese Patent Application Publication No. 2002-110121).
Further, electronic devices having a battery housing chamber for accommodating the battery device is also available.
This type of battery housing chamber is structured with a width corresponding to the width of the battery device, a height corresponding to the case thickness, a depth corresponding to the case length, and a housing side chamber terminal to be in contact with the battery side terminal when the battery device is aligned with chamber and inserted therein.